Effect of the organic solvent polarity on the structure of the gold nanoparticle adsorption layer as observed by photon-correlation spectroscopy

摘要

Spherical gold nanoparticles with the metal core of 5nm in diameter (according to the data of the transmission electron-microscopy) are prepared by the reduction of chloroauric acid with hydrazine monohydrate in reverse micelles of sodium bis-(2-ethylhexyl sulfosuccinate) (AOT). The photon correlation spectroscopy (PCS) method is used to determine the structure of the gold nanoparticle adsorption layer after their concentration and redispersion in AOT solutions in organic solvents with different polarity (in a series of decane, toluene, and chloroform). It is shown that in case of the abovementioned solvents at low AOT concentrations a gold nanoparticle is surrounded by a monolayer consisting of AOT molecules. When the concentration increases up to 1 M, the absorption layer thickness sharply increases; an increase in the organic solvent polarity enhances this increase. An increase in the temperature (from 20A degrees C to 55 A degrees C) leads to a partial and reversible decrease in the absorption layer thickness.